1. Field of the Invention
The invention relates to a method for transmitting high rate real-time streaming data in a communications system.
2. Description of the Related Art
Designing a Media Access Control (MAC) protocol for a wired or wireless link is a really important task in a communications system, and most MAC protocol is designed for transmitting compressed low rate streaming data. It has been quite challenging to design for high rate real time steaming data because the high rate real-time streaming data contains some unique characteristics. A high rate real-time streaming data comprises a sequence of data packets forming a data flow arrived at a constant rate. The high rate real-time streaming data arrives at a communications device isochronously. The term isochronous means that data packets usually appear regularly according to a predetermined frequency, and each data packet has a predetermined duration. Importantly, there is no flow control to throttle the data traffic between source and destination communications device. Once the flow of a high rate real-time streaming data starts, the latency of each data packet must meet a strict time constraint. Otherwise, the data packet is determined as being lost. The latency of a data packet is the time period between the arrival time at the source communications device and the departing time from the destination communications device.
A high definition video stream, for example, a high definition video stream in compliance with a High Definition Multimedia Interface (HDMI) protocol, is one kind of high rate real-time streaming data. Different from compressed video streams, such as the video streams compressed according to MPEG 2 (Moving Picture Experts Group) or MPEG 4 standards having low data rates of about 20 Mbit/sec, the high definition video stream has extremely high data rates up to 3 Gbit/sec or more. The extremely high data rate requires a large amount of transmission bandwidth. In addition, for proper operation, it is critical to design an efficient re-transmission scheme without degrading overall data packets transmissions. Moreover, it is also critical to achieve and maintain high utilization rate of channel resources. Because of the high rate real-time streaming data consumes a large portion of channel bandwidth, a low utilization rate may render the channel unusable for the high rate real-time streaming data.
Therefore, in order to achieve better channel utilization in compliance with the real-time constraint for high-rate real time streaming data, a novel MAC protocol and re-transmission mechanism is highly required.